1. Field of the Invention
The present invention relates to a driving mechanism, and more particularly to a door driving mechanism.
2. Description of the Prior Art
A typical door driving mechanism is shown in FIGS. 7 and 8 and is provided for driving a door, for example, as shown in FIG. 6, the door 50 includes a number of wheels 51 rotatably engaged on a pair of tracks 52 and includes a number of door frames coupled together by a lazy tong construction 53, the typical door driving mechanism comprises a plate 54 fixed in the lower portion of one end of the door 50, a reduction gearing 55 and a motor 56 disposed on the plate 54, a sprocket 57 connected to the reduction gearing 55, a pair of wheels 60 rotatably secured to the plate 54 by a shaft 61, and another sprocket 59 fixed on the shaft 61 and coupled to the sprocket with a chain 58, the wheels 60 are rotated by the motor 56 via the chain 58 and the sprockets 57, 59. However, in operation, the chain 58 applies an upward pulling force to the sprocket 59 such that the wheels 60 may also be slightly pulled upward away from the tracks the frictional force between the wheels 60 and the tracks 52 will thus be reduced such that the door can not be stably driven by the motor. In addition, when the door is closed, no lock devices are provided for retaining the door in the closed position, the wheels 51, 60 may easily slide along the tracks 52 when the door is pushed.
The present invention has arisen to mitigate and/or obviate the afore-described disadvantages of the conventional door driving mechanisms.